David Wright #5 of the New York Mets looks on against the Milwaukee Brewers at Citi Field on Thursday, June 12, 2014 in the Queens Borough of New York City. Photo Credit: Jim McIsaac

PITTSBURGH - David Wright held out hope yesterday that he'll be sidelined for only a few days, that the pain in his left shoulder might subside with rest, a cortisone shot and stronger anti-inflammatory medication.

But the status of the Mets' most accomplished player will remain in flux until he can undergo an MRI exam today in New York in hopes of discovering the root of what he called a "fairly painful" injury that he's endured the last two weeks.

A late scratch before last night's 3-2 walk-off loss against the Pirates, Wright insisted the injury did not hamper his performance until Thursday night, when the pain worsened after a pair of plays he made in the field.

"It was something I could play through and still feel like I could be productive out there, which wasn't an issue," said Wright, who was replaced in the lineup by Eric Campbell.

Wright's injury was just the start of a particularly frustrating day for the Mets, who lost in the 11th inning when Josh Harrison doubled to drive in Clint Barmes, who had reached on a four-pitch walk by Vic Black.

Until then, the Mets and Pirates had engaged in a bullpen standoff, with Jenrry Mejia working out of a bases-loaded jam in a wild 10th inning. Harrison triggered a controversy when he slipped out of a pickle by ducking under a tag by Ruben Tejada. The incident infuriated Mets manager Terry Collins, who argued to no avail that Harrison had left the basepath.

Later, Harrison ended it with his game-winning hit, a final twist of the knife for the Mets.

Though he couldn't pinpoint the exact date of his injury, Wright appeared to hurt his shoulder during a June 12 home game against the Brewers. He slid headfirst on a steal of second base and jammed his shoulder into the muddy dirt.

The Mets were not aware of the severity of the injury. Two days ago, they demoted infielder Wilmer Flores, a natural replacement if Wright winds up needing a few days. Now the Mets will be able to immediately promote Flores only if Wright winds up on the disabled list.

If Wright doesn't go on the DL, the Mets will stick with their current roster configuration, even though they'll be down an infielder while carrying an extra outfielder.

Collins said he was not aware until Friday that Wright's shoulder had been bothering him. "I absolutely salute him for coming in and saying something today," said Collins, who noted Wright's history of playing through injuries.

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To keep playing, Wright had been taking anti-inflammatory medication and doing extra work in the trainer's room. That formula seemed to work. Since June 13, he has posted a .319/.358/.574 slash line with two homers and nine RBIs, climbing out of a horrendous slump.

But the status quo changed Thursday night. Wright said his shoulder flared up on two plays: when he reached to tag Ike Davis in a rundown and when he stretched to make a play on a grounder by Pedro Alvarez.

Still, the captain "was hoping to be able to push through it" before the training staff "shut that down."

Wright originally was in last night's lineup, but as he went through his pregame routine, the trainers noticed something was wrong.

"Some things were hurting a little more than usual," said Wright, who is hitting .277 with six homers and 41 RBIs. "That's when they kind of took it out of my hands and wanted me to go get an MRI and make sure that it doesn't get any worse."

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